Circuit breaker



Aug. 31, 1943. JACKSON ET AL 2,328,458

CIRCUIT BREAKER Filed Nov.v '7, 1940 3 Sheets-Sheet 1 E INVENTORS G. HKSON JOHN C SENS \J DLRV M v BY ATTO EY 1943- J. G. JACKSON ET AL2,328,458

G IRGUI'I' BREAKER Filed Nov. 7, 1940 s Sheets-Sheet 2 F INVENTORS JOHNG JHCKSON OLFIV MFISENG ATTOR EY 1943- J. G. JACKSON ET AL 2,328,458

C IRCUIT BREAKER Filed Nov. '7, 1940 5 Sheefs-Sheet s v iii i .INVENTORSJOHN G-JHCKSON DLHV MRSENG Patented Aug. 31, 1943 CIRCUIT BREAKER JohnG. Jackson and Olav Maseng, assignors to Square D Company,

Detroit, Mich, Detroit, Mich,

a corporation 01' Michigan Application November 7, 1940, Serial No.364,630

9 Claims.

This invention relates to electrical circuit controllinginstrumentalities, and more particularly to circuit breakersautomatically operable to open the circuit upon the occurrence ofcurrent overloads.

One object of this invention is to provide an improved form of currentresponsive releasing means for a circuit breaker which simply, buteflectively, combines the action of a thermally responsive memberoperating primarily on light overloads and a magnetically responsivemember operating primarily on relatively heavy overloads.

Another object of the invention is to provide an electromagnetic circuitbreaker with a combined thermal-magnet tripping device in which both thethermally and magnetically responsive elements operate on means forlatching a releasable part on the breaker.

Another object of the invention is the provision in an automaticelectric circuit breaker of a magnetically responsive member, with orwithout a combined thermally responsive member, which is. mounted toexert a force multiplying unlatching bias on the latching element of thecircuit breaker.

Another object of the invention is the provision in an automaticelectric circuit breaker or a magnetically responsive member, with orwithout a combined thermally responsive member, which has a lost motionconnection with a latching element for the breaker so that movement ofthe magnetic member will strike a sharp blow on the latch to initiateits unlatching movement.

Other objects and features of this invention will be readily apparent tothose skilled in the art from the following specification and appendeddrawings illustrating certain preferred embodiments in which:

Figure l is a vertical sectional view through a circuit breakeraccording to the present invention.

Figure 2 is a front elevational view of the circuit breaker according tothe present invention with the front cover removed.

Figure 3 is a partial sectional view similar to Figure 1, and showingthe parts at the instant the breaker mechanism is automaticallyreleased.

Figure 4 is a fragmentary perspective view of the latching element andmagnetically responsive member of the circuit breaker of Figures 1Figure 5 is a perspective view responsive member and the net or thecircuit breaker of the thermally stationary field magof Figures 1 to 3.

Figure 6 is a detailed side view of a modified form of currentresponsive releasing means.

Figure 7 is a sectional view on the line VII- VII of Figure 6.

Figure 8 is a detailed side view of a simplified form of the currentresponsive releasing means.

Figure 9 is a sectional view on the line IX-IX of Figure 8.

In the drawings, the current responsive tripping means of this inventionhave been illustrated in connection with a multipole circuit breakergenerally similar to that disclosed in Patent 2,096,544, granted October19, 1937, for Circuit breaker. It is, however, to be understood that thecurrent responsive tripping means may be utilized in connection withother forms of circuit breaker mechanisms which may include eithersingle or multipole construction and the particular mechanism shown isby way of example in compliance with the patent statutes.

The circuit breaker herein illustrated comprises a base I having aplurality of individual compartments therein for the individual poles ofthe breaker. End ledges 2 and ID are provided at the ends of each polecompartment. Upon the upper ledge 2 of each pole is mounted a connector3 by means of a spun over portion of a metallic insert 4. At the innerend of this con- I nector is disposed a stationary contact 5 within anarc chamber formed by insulating walls 6, the upper wall 6 furtherserving to seal off the upper end of the pole compartment. Through aslot in the lower wall 6 extends a contact carrying bar I having acontact 8 thereon cooperating with stationary contact 5. The bar I isprovided with a notch 20 engaging in an elongated notch in a leg of areciprocable member 9. A compression spring ll biases the bar 1 in theupward direction.

The opposite end of the bar 1 is normally restrained by a latch l2secured at its front end within a shaft l3 which is common to all thepoles of the multipole form of breaker. The latch l2 may be rigidlyconnectedto the shaft I3 as in Patent 2,096,544, aforesaid, or a limitedlost motion may be provided so that the current responsive means willhave the unlatching resistance of only one latch as disclosed andclaimed in Patent 2,132,629, granted October 11, 1938, for Circuitbreaker. A spring l4 biases the latch l2 into latching position. Thelatch I2 is of general L-shape and is provided with an abutment toe I 5adapted to be engaged by a bimetallic element 16 which is mounted upon aconnector I1 secured to the lower end ledge 3 by a spun over portion ofa metallic insert I8. The free end of the connector I! is movable by astud I9 to determine the position of the bimetal element I6 and hencethe calibrating point for the circuit breaker pole. A flexible lead 2Iinterconnects the free end of the bimetal element IS with the bar I.Upon the connector I1 is mounted a'generally U-shaped magnetic piece 22having its legs disposed on opposite sides of bimetallic element I6.Upon the latch I2 is pivoted a magnetically responsive armature member23, these parts being shown in perspective view in Figures and 4respectively. The magnetically responsive armature member 23 is pivotedon the latch I2 by being pivoted on a shaft 24 which is welded orotherwise secured to the latch. The front portion 25 of the element 23constitutes the armature which is attracted toward the field magnet 22upon the passage of a predetermined overload current through thecircult; breaker. This movement of the armature 25 effects rotation ofthe element 23 with respect to the latch I2; however, the back portion26 of the element 23 bears against the end of the bar I and as the baris restrained from moving longitudinally, the portion 26 will beprevented from movement with respect to the bar and other parts. As aresult of the bias to rotate the element 23 and the holding of the backportion 26, the net result is a rotation of the latch I2 in a clockwisedirection; and, since the distance from the pivot pin 24 to the backportion 26 is less than the distance from the armature 25 to the backportion 26, a force multiplying action will be exerted which willenhance the effectiveness of the magnetically operated releasing means.

The pole compartments are sealed at their lower ends by insulatin walls21 and the circuit breaker is manually operated with an operating member28 common to all poles of the breaker and which carries a plurality ofcamming portions 23 cooperating with the front face of the recip cableelements 9 to effect manual operation of the breaker as well asresetting after an automatic opening. The breaker is closed againstaccess by an insulating sheet 3I and a front metallic cover 32 sealed tothe base.

The manual operation of the circuit breaker is identical with thatexplained in connection with my previous patents cited heretofore. Theoperation of the breaker on low overloads is also the same as in myprevious patents, since the passage of this low overload current throughbimetaii I6 causes it to flex in a clockwise direction to move the latchI2 into unlatching position, whereupon the bar I also rotates in aclockwise direction under the action of spring I I to automatic circuitopen position. As previously explained, the latches I2 of the multipolebreaker may be rigidly connected to the common shaft or may have alimited lost motion connection therewith. Where the latches have thepositive connection, the movement of the latch I2 by a cooperatingbimetal through which an overload is passing also effects immediaterotation of the shaft I3 and consequent movement of all other latchesI2, whether their bimetals are connected or not. Accordingly, all of thebars 1 or all the breaker poles will be released, and consequently allthe contacts of the breaker open upon the occurrence of an overload, inone or all of the poles. Where a limited lost motion is provided betweeneach of the latches I2 and a common shaft I3, each latch I2 will bemoved by its associated affected bimetal independently of the shaft I3and of the other latches into a position where it unlatches itsassociated bar I. Then, as the bar I rotates into open position, iteffects a further movement of its latch I2, and as the lost motion isprovided to be taken up at the point of latch release, the common shaftI3 will be rotated by this further movement of the releasing latch I2and the rotation of the shaft I3 will effect unlatching movement ofother and unaffected latches I2 in the same manner as where the latchesand common shaft are rigidly connected. This unlatching operation in theautomatic opening of the breaker is the same for both thermal andmagnetic response, it being understood that the magnetic release iseffected by the magnetic elements previously described and that thelatch movement may be independent of and relative to the seriallyconnected bimetal I6. On low overloads the circuit breaker will beprovided with the desired time lag in its operation. However, on heavyoverloads and short circuit, the opening operation of the breaker willbe magnetic and without delay. The magnetic parts can be seen to beextremely simple, requiring only the embracing of the current path toproduce the desired operation. Further, the force multiplying actionthrough the pivoting of the element 23 provides the desired unlatchingforce without a definite winding and with only a relatively small amountof iron in the magnetic circuit.

Figures 6 and. 7 show a modified form of the invention in which thepivoted element 23 has been replaced by an armature element 33 which ismounted on the latch I2 by means of a light spring 34 which gives it arelatively light bias against the latch I2. Rigid with the armature 33is a C-shaped bracket 35 whose open arms 36 are adapted to engage theback surface of the latch I 2 but which are normally held spacedtherefrom by the small bias of the spring 34. This construction providesfor a lost motion between the latch I2 and the armature 33 so thatinitial movement of the armature takes place without moving the latchand the initial latch movement is effected by a hammer blow from theengagement of the moving armature arms 36 therewith.

The constructions of Figures 1 to 5 and Figures 6 and 7 are similar withthe main difference that the preferred embodiment incorporates aforce-multiplying, prying action for the unlatching movement whereas thestructure of Figures 6 and 7 relies on a light hammer blow to overcomestatic friction and to initiate the unlatching movement.

In Figures 8 and 9 a greatly simplified form of the invention is shownwhich will be sufficient for certain applications. Here the armature 31is mounted directly on the latch I2 and upon the attraction of thearmature 31 the latch I2 will be bodily moved therewith. While the latch31 in this embodiment is shown as a piece added to the latch I2, it isunderstood that the latch I2 may itself serve as the armature if it isof sufficient size to produce the desired magnetic force. Thisembodiment is, of course, the simplest but it requires a greatermagnetic effect before the unlatching movement is secured, since it hasneither the prying action of the preferred embodiment nor the lighthammer blow of the embodiment of Figures 6 and 7.

While certain preferred embodiments of this invention have beenspecifically disclosed, it is understood that the invention is notlimited thereto, as many variations will be readily apparcut to thoseskilled in the art and the invention is to be given its broadestpossible interpretation magnetic circuit energized in response tocurrent flow through the breaker and adapted to attract said armatureelement to effect movement of the latching means to unlatching position,and means biasing said armature element with respect to the latchingmeans into a position remote from the magnetic circuit wherebyattraction of the armature element is initially effected without movingthe latching means so that the armature element engages the latchinmeans with a hammer blow to initiate its movement to unlatchingposition.

2. In an automatic electric circuit breaker, cooperating contactscontrolling the a circuit through the breaker, means releasable toefl'ect separation of said contacts to open the circuit,

means for latching said releasable means, means biasing said latchingmeans into latching position, a bimetallic element connected in seriescircuit with said contacts and operating in response to a predeterminedcurrent to move the latching means into releasing position, an armatureelement having a lost motion connection with said latching means,astationary magnetic circuit energized in response to current flowthrough the breaker and adapted to attract said armature element toeilect movement 01' the latching means to unlatching position, and meansbiasing said armature element with respect to the latching means into aposition remote from the magnetic circuit whereby attractionof thearmature element is initially effected without moving the latching meansso that the armature element engages the latching means with a hammerblow to initiate its movement to unlatching position.

3. In an automatic electric circuit breaker, cooperating contactscontrolling the circuit through the breaker, means releasable to effectseparation of said contacts to open the circuit, means for latching saidreleasable means, means biasing said latching means into latchingposition, a bimetallic element connected in series circuit with saidcontacts and operating in response to a predetermined current to movethe latching means into releasing position, an arma ture element mountedon said latching means by a limited lost motion connection providing forrelative movement therebetween, a stationary magnetic circuit adapted toattract said armature to move the latching means to unlatching position,means biasing the armature with respect to latching means in thedirection of latching move.- ment, said spring bias being less than theresistance ofiered by the latching means to unlatching movement wherebyinitial movement of the armature will be effected without moving thelatching means so that the armature will become engaged with thelatching means while it is in motion to effect a hammer blow to initiatethe opening movement of the latching means.

4. In an automatic electric circuit breaker, cooperating contactscontrolling the circuit through the breaker, means releasable to eflectseparation or said contacts to open the circuit, means for latching saidreleasable means, means biasing said latching means into latchingposition, an armature element pivotally mounted on said latching meansat a point intermediate its ends, a stationary magnetic circuitenergizedin res onse to current flowing through the breaker and positioned toexert a magnetic i'orce upon one end of said armature element, theopposite end of said armature element engaging a part stationary atleast during the unlatching movement, whereby a force multiplying,prying action is exerted on said latching means in response to theattraction of said armature element by the magnetic circuit.

5. In an automatic electric circuit breaker, cooperating contactscontrolling the circuit through the breaker, means releasable to efiectseparation of said contacts to open the circuit, means for latching saidreleasable means, means biasing said latching means into latchingposition, an armature element pivotally mounted on said latching meansat a point intermediate its ends, a stationary magnetic circuitenergized in response to current flowing through the breaker andpositioned to exert a magnetic force upon one end of said armatureelement, the opposite end 01' said armature element engaging with saidreleasable means as an abutment whereby a force multiplying pryingaction is exerted on the latching means in response to the attraction ofthe armature by the magnetic circuit.

6. In an automatic electric circuit breaker, cooperating contactscontrolling the circuit through the breaker, means releasable to eflectseparation of said contacts to open the circuit, means for latching saidreleasable means, means biasing said latching means into latchingposition, a bimetallic element connected in series circuit with saidcontacts and operating in response to a predetermined current to movethe latching means into releasing position, an armature elementpivotally mounted on said latching means at a point intermediate itsends, a stationary magnetic circuit energized in response to currentflowing through the breaker and positioned to exert a magnetic forceupon one end of said armature element, the opposite end of said armatureelement engaging a part stationary at least during the unlatchingmovement, whereby a force multiplying, prying action is exerted on saidlatching means in response to the attraction of said armature element bythe magnetic circuit.

7. In an automatic electric circuit breaker, cooperating contactscontrolling the circuit through the breaker, means releasable to eflectseparation of said contacts to open the circuit, means for latching saidreleasable means, means biasing said latching means into latchingposition, a bimetallic element connected in series circuit with saidcontacts and operating in response" to a predetermined current to movethe latching means into releasing position, an armature elementpivotally mounted on said latching means at a point intermediate itsends, a stationary magnetic circuit energized in response to currentflowing through the breaker and positioned to exert a magnetic forceupon one end of said armature element, the opposite end of said armatureelement engaging with said releasable means as an abutment whereby aforce multiplying prying action is exerted on the latching means inresponse to the attraction of the armature by the magnetic circuit.

8. In an automatic electric circuit breaker,

cooperating contacts controlling the circuit through the breaker, meansreleasable to effect separation of said contacts to open the circuit, abimetallic element having relatively fixed and free ends, a latchingmember extending substantially parallel to said bimetallic element andpivoted at one end adjacent the fixed end of said bimetallic element andhaving its free end engaging the free end of the bimetallic element soas to be moved thereby in one direction and movable relative thereto inthe same direction, said latching member engaging and latching saidreleasable means, and a stationary field magnet embracing a current paththrough the breaker so as to be energized in response to flow of currenttherethrough and operative to effect movement of said latch member inresponse to the flow of an overload current and operative to move saidlatch member independently of the bimetal.

9. In an automatic electric circuit breaker, cooperating contactscontrolling the circuit through the breaker, means releasable to effectseparation of said contacts to open the circuit, a bimetallic elementhaving relatively fixed and free ends, a latching member extendingsubstantially parallel to said bimetallic element and pivoted at one endadjacent the fixed end of said bimetallic element and having its freeend B11888- ing the free end of the bimetallic element so as to be movedthereby in one direction and movable relative thereto in the samedirection, said latching member engaging and latching said releasablemeans, a stationary field magnet embracing a current path through thebreaker so as to be energized in response to flow 01 currenttherethrough, and an armature element mounted on said latch member in aposition to be attracted by said field magnet in response to the flow ofan overload current and operative to move said latching memberindependently of the bimetal. said armature being movable relative tosaid latching member in its attracted movement so as to facilitate atleast the initial unlatching movement of the latching member.

' JOHN G. JACKSON.

OLAV MASENG.

